In an earlier article we presented an innovative approach for introducing mechanics at upper secondary level based on the idea of tapping core causal knowledge, and we described the working of the first part of the module. In this article we describe the second part of the module, in which we make use of the students' intuitive plausibility judgements to direct and guide a systematic evaluation of alternative theories, leading towards a justified choice of Newton's theory of planetary motion. Outcomes of our study to investigate the working of the module in classroom practice are also summarized. [For earlier article, see EJ802502.] (Contains 1 footnote, 1 table, and 6 figures.)